This invention relates to a wireless communication system such as a cellar network system in which relay nodes are deployed, and more particularly, to a wireless communication system, and a dynamic association control apparatus and a dynamic association control method for performing load transfer by using relay nodes.
In recent years, with rapid development of wireless communication technologies, cell area in a cellular network is being zoomed out, and the network load sharply increases, which results in the cell load dramatically varying in time domain and space domain. With such load non-uniformity, on one hand quality of service (QoS) for users in hot cells degrades, and on the other hand resources in non-hot cells are not fully utilized. To address the issue of the degradation of QoS for users in the hot cells, the load within the hot cells needs to be transferred to the surrounding non-hot cells, i.e., the operation of performing load transfer in the network is desired.
For example, Patent Literature 1 (WO2012/016590A1) “DISTRIBUTED LOAD BALANCING IN CELLULAR WIRELESS NETWORKS” discloses a method for transferring load in a cellular network. This method is based on a distributed algorithm, and transfers the load by changing the base station that serves users.
In addition, a relay technology of setting relay nodes which belongs to a base station serving a cell has become one of the widely accepted wireless communication technologies in recent years. In several cellular network standards, the relay technology has been incorporated. The so-called relay node refers to a device that is associated with a base station of a cell corresponding to a range of setting, and is typically deployed at edges of the cell for enhancing signal strength of edge users and extending coverage.
The distributed algorithm disclosed in Patent Literature 1 (WO2012/016590A1) only involves load transfer between users and the base station, but does not involve a relay node.
In addition, Patent Literature 2 (WO2012/015411A1) “SYSTEM AND METHOD FOR MOBILE ACCESS CONTROL AND LOAD BALANCING IN A RELAY NETWORK” discloses a method for transferring load using a relay within a single cell including relay node.
However, this method cannot be applied to a scenario of load transfer between different cells among a plurality of cells. In the cellular network environment, the problems of uneven resource allocation and blocking cannot be solved.
Additionally, Patent Literature 3 (US2003/0068975A1) “Integrated cellular and ad hoc relaying system” discloses a cellular network in which relay nodes are deployed, and reveals that the deployed relay nodes can help transfer load among a plurality of cells. However, no specific algorithm for the relay node to transfer load is given.